When using a crane and a system of cables to lift, and otherwise handle heavy loads such as boats, pressure vessels, refinery components and various modules used in the fabrication of offshore drilling rigs and the like, it is a typical practice to use one or more horizontal spreader pipes or bars to control the geometry of the lifting cables. For example one pair of equal length cables may incline in opposite directions from the hook and traveling block to the respective outer ends of the spreader bar, while another pair of such cables extend vertically from the respective outer ends of the bar to the load being lifted. The spreader bar protects the load by keeping the cables away from it during lifting. To increase the number of lift points, other cable and spreader bar sets can be suspended from the ends of an upper spreader bar and form a cascade of lifting units at right angles to one another with the lowermost cables being vertical and coupled at spaced points to the load. When the load is picked up, each spreader bar is placed under high compression loading as it maintains the separation between the lower ends of the inclined cables above it.
The compression end cap assemblies by which the cables are connected to a spreader bar or pipe are a very important component in the design of the above type of lifting equipment, because failure of a cap or buckling of a spreader pipe can cause a potentially disastrous situation to exist. Although a number of different types of cap designs have been used, problems remain. For example, a known design requires the use of shackles for each cable connection point, which are quite heavy and expensive and increase rigging time. Any change in spreader span or length in the field requires welding which is time consuming and expensive. Some spreader bar designs have not been reusable or adaptable to other lifting situations, were difficult to rig up, and could require an extra crane for their handling.
An object of the present invention is to provide a new and improved compression cap assembly for a spreader bar that obviates the above-mentioned problems.
Another object of the present invention is to provide a new and improved compression cap assembly that eliminates the need for using shackles or similar connecting devices, together with their extra weight.
Still another object of the present invention is to provide a new and improved compression cap assembly that is much easier to install on the end of a spreader pipe, thereby minimizing down time.
Yet another object of the present invention is to provide a new and improved compression cap assembly that is constructed and arranged to permit change in spreader bar span in the field without time consuming and expensive fabrication including welding.